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SCIENCE

D

uring the 1920s and 1930s, Vien-

nese physician and adventurer 

Alfons Gabriel fell under the 

spell of Iran’s Lut Desert. Gabriel 

had crisscrossed arid parts of the 

Middle East, Pakistan, and Af-

ghanistan by camel, observing 

and mapping areas into which few 

dared venture—lands with names 

such as Dasht-i-Naumid (the Desert with-

out Hope) and Dasht-i-Margo (the Desert of 

Death). But a “confused mass of impassable 

tangled dunes” stymied his efforts to probe 

the interior of the Lut Desert, a tract of sand 

and fantastical rock formations in southeast-

ern Iran that was said to be the hottest place 

on Earth.

In March 1937, Gabriel finally conquered 

the central Lut—and barely made it out alive. 

He described his experiences a year later in a 

spellbinding talk to the Royal Geographical 

Society in London. Late one afternoon, 

Gabriel recounted, “the landscape darkened 

under red clouds … and a noise like the roar-

ing of the sea began.” The dust storm raged 

into the night. “For several anxious hours we 

lay, motionless and helpless, outstretched on 

the ground.” Later, the voyagers were dis-

oriented by mirages that were most vivid 

when the air was coolest, just before sunrise. 

Near the end of the 3-week journey, even 

their parched camels had had enough: “Their 

legs trembled; they panted, knelt down, and 

sometimes crept along on their knees.” 

The allure of the Lut persists. Last month, 

a convoy of five SUVs carried 10 researchers 

and their guides, along with cameras, instru-

ments, and hundreds of liters of water and 

fuel, into the heart of the desert. These mod-

ern explorers from Iran, the United States, 

and Europe were drawn not so much by the 

exotic landscape as by the puzzle of its un-

usual ecosystem. Many researchers had as-

sumed that the Lut Desert is too hostile to 

sustain life, says Hossein Akhani, a plant 

biologist at the University of Tehran. The in-

terior of the desert, an area nearly as big as 

West Virginia, is mostly devoid of plant life. 

But adventurers and the occasional scientist 

who traveled into the Lut had spotted di-

verse animal life, including insects, reptiles, 

and desert foxes. How that food web holds 

together without plants has been a mystery.

A morbid, and possibly unique, phenome-

non may be the answer. Dead birds are a fre-

quent sighting in the desert. A few years ago, 

scientists in Iran began wondering whether 

migratory birds stray into the Lut and, over-

come by the intense heat, fall from the sky 

like manna, forming the base of a food web. 

The expedition, organized by Akhani and 

Bahman Izadi, head of an environmental 

nonprofit in Shiraz, Iran, and a Lut explorer, 

Iran’s Lut Desert—Earth’s hottest—is devoid of plants 

but somehow sustains a vibrant ecosystem

By Richard Stone; Photography by Bahman Izadi

SOME LIKE IT HOT

F E AT U R E S

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set out to test the idea. Colleagues warned 

that in the fall, right after the heat of sum-

mer, the team might not find enough living 

things to tell. Creatures that burrowed or mi-

grated to escape the heat would not have had 

time to venture back into the desert. 

Instead, the team confirmed the existence 

of a vibrant ecosystem and saw compelling 

signs that migratory birds do help nourish 

it. They also found that the bone-dry land-

scape conceals what they are calling a “hid-

den sea”: a surprisingly shallow layer of salty 

groundwater that may also help sustain life.

The Lut Desert also offers a less uplifting 

lesson—at least for people living on the knife 

edge of sustainability in arid regions. Climate 

change models predict that as temperatures 

rise, tracts of the Middle East that are natu-

rally uninhabitable—not survivable without 

air conditioning—will expand. Those areas 

may come to resemble the transition zone 

between settlements on the Lut’s edges and 

its supremely hostile core.

AFTER GABRIEL’S PIONEERING VENTURE

, the 

scientific literature on the Lut Desert re-

mained sparse. One point was settled, though: 

Gabriel had noted that a contemporary, the 

German geographer Gustav Stratil-Sauer, 

“was of the opinion that the hottest re-

gion of the earth was not, as hitherto sup-

posed, to be found in Sind, or Abyssinia, or 

in the Death Valley of California, but in the 

southern Lut.” In 2005, an infrared radio-

meter on NASA’s Aqua satellite measured 

a ground temperature of 70.7°C (159.3°F) 

at one spot in the Lut—the hottest satellite 

reading of ground temperature ever. And in 

April 2014, Morteza Djamali, a paleoecologist 

at the Mediterranean Institute of Marine and 

Terrestrial Biodiversity and Ecology in Mar-

seilles, France, and his colleagues ventured 

into the central Lut to install a temperature 

logger at the same spot. In an experience 

worthy of Alfred Hitchcock, a swarm of lo-

custs descended, picking nearby bird car-

casses clean, cannibalizing each other, and 

biting the researchers. “I can imagine that a 

lonely traveler could be killed by these small 

creatures” in a few days, Djamali says.

The hardship paid off, Djamali says. In 

July, the thermometer, planted 30 centi-

meters above the surface in the shade of a 

wooden cylinder, registered 61°C—some 

5°C higher than the official shade record 

set in Death Valley in 1913. Bands of heat-

absorbing black sand, primarily magnetite, 

together with topography that limits air 

movement help explain the blazing tempera-

tures, Djamali says.

That same year Akhani paid his first visit 

to the Lut, a quick scouting trip. A special-

ist in salt-loving plants, which grow in salty 

seeps in a few spots in the desert, he also had 

noticed the birds’ carcasses and wondered 

what role they might play in the ecosystem. 

Cobbling together backing from the Iranian 

National Science Foundation, the Saeedi 

Institute for Advanced Studies at Kashan 

University in Iran, and other sources, he as-

sembled a team of specialists from Iran and 

abroad that will spend the next 5 years priz-

ing scientific secrets from the desert.

THE TEAM SET OFF LAST MONTH

 on its maid-

en expedition, departing from Shahdad, an 

oasis on the Lut’s western edge, and head-

ing due north before arcing south in 

a path that bisected the desert (see 

map, left). In some areas, yard-

angs, wind-sculpted rock forma-

tions several meters tall, sprouted 

from the desert like mushrooms. 

Heftier formations called kaluts 

reminded Akhani of “the ruins of an 

old city.” Relics of what Djamali calls a 

“complex geoclimatic history,” some are 

made of sandstone, whereas others were 

eroded from the beds of saline and playa 

lakes that dotted the landscape some 

10 million years ago. The topography, 

whimsical or majestic, is a major reason 

Tehran

Bam

Keshit

Shahdad

Expedition route

Lut Desert

Caspian

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Persian 

Gulf

SAUDI 

ARABIA

IRAN

IRAQ

KUWAIT

Km

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250 500

The Lut Desert’s fantastical 

landscape harbors creatures that 

eke out a living from hidden water 

and the occasional windfall.

Empty quarter

Few scientists had probed the heart of the Lut Desert.

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the United Nations Educational, Scientific 

and Cultural Organization inscribed the 

Lut Desert on its World Heritage List last 

July. (Iran hopes it will beckon intrepid 

ecotourists.) Along their 700-kilometer 

journey, the researchers sampled soil 

and biota at 37 sites before emerging 

from the desert east of Bam, a city that 

suffered catastrophic damage from a 

2003 earthquake.

One day, the team struck out on foot into 

a canyon called Zabone Mar, which means 

“snake’s tongue.” By satellite, the canyon, 

about 15 meters wide with walls reaching 

30 meters high, looks like a bifurcated 

tongue. “I noticed a weird noise,” recalls expe-

dition member Amir AghaKouchak, a hydro-

logist at the University of California (UC), 

Irvine. A continuous, soft crackling ema-

nated from the walls. He speculates that the 

sound was the rock expanding as tempera-

tures soared from nightly lows near 0°C up 

to fall daily maximums of about 40°C. “I just 

stopped and listened to this beautiful music.”

Or perhaps it was a siren call: The canyon 

is a death trap. Within its walls, the research-

ers found the remains of dozens of migratory 

birds. The birds may have sought shelter in 

the canyon’s shade, but without water they 

would have quickly perished, AghaKouchak 

says. Mahmoud Ghasempouri, an ornitho-

logist at Tarbiat Modares University in Teh-

ran, collected carcasses of several migratory 

species. Why the birds make a fatal detour 

into the desert is a puzzle, he says. Even out-

side the canyon dead migratory birds were 

plentiful, and they often bore signs of hav-

ing been scavenged by foxes. “I think that’s 

their main food source,” AghaKouchak says.

Insects, too, are critical to the Lut’s food 

web. Many nibble on plants on the desert’s 

periphery and are in turn eaten by spiders, 

reptiles, and foxes in the Lut’s interior, 

supplementing the nutrients in the ill-fated 

birds, says expedition member Hossein 

Rajaei, curator of Lepidoptera—moths and 

butterflies—at the Stuttgart State Museum 

of Natural History in Germany. Yet some live 

in the heart of the desert. When Rajaei set 

up light traps at night, he was surprised to 

count large numbers of moth species. “What 

do they do there? What do they eat there?” 

he asks. How the fly larvae he found in a 

pool of hypersaline water survive is another 

enigma, he says. And so is the question of 

how the Lut’s denizens stay hydrated.

The answer may lie just below the surface. 

Before the expedition began, AghaKouchak 

had scrutinized satellite sensor data from 

the Lut. To his surprise, microwaves emanat-

ing from the ground suggested that in some 

parts of the oven-hot desert, the soil is moist. 

Perplexed, AghaKouchak consulted a col-

league, who proposed that the Lut’s soil is 

so dry that microwaves were radiating from 

deeper layers of soil or even rocks, falsely 

indicating shallow moisture.

Last month, in the heart of the desert, 

the team’s convoy entered “a flat landscape, 

as far as you can see,” the hydrologist says. 

A short distance onto the plain, one of the 

trucks broke through several centimeters of 

hard, crusty soil and sank, up to its axles—

in mud. After another SUV pulled out the 

stricken vehicle, “you could actually see wa-

ter” where the tires had been. “It was hard to 

believe,” AghaKouchak says, “but the area is 

really, really wet.”

He thinks the moisture comes from dis-

tant mountains that ring the table-flat playa. 

Occasional rainfalls in the spring and early 

fall drain into the flat basin, he says. Accord-

ing to the team’s guides, other areas of the 

Lut have similar features. Back at UC Irvine, 

AghaKouchak will attempt to correlate the 

local knowledge with satellite moisture data 

to map the extent of the hidden sea. 

NO ONE LIVES 

in the heart of the Lut, and af-

ter a 6-year-long drought in Iran, settlements 

on the desert’s fringes are in retreat. That 

may foreshadow the fate of other parts of the 

Middle East as global warming pushes sum-

mer temperatures still higher, says Elfatih 

Eltahir, an environmental engineer at the 

Massachusetts Institute of Technology 

in Cambridge. 

Last year, in Nature Climate Change, 

Eltahir and a colleague defined a naturally 

uninhabitable climate as one in which 

the heat index—temperature adjusted for 

humidity—exceeds 35°C for more than six 

straight hours. “What we are talking about 

are really extreme conditions,” Eltahir says. 

“If a human being is exposed to that, very 

likely that person would die.” 

In summer, areas of the Persian Gulf al-

ready exceed that threshold and would 

be unbearable without air-conditioning. 

Barring “significant mitigation,” the un-

inhabitable areas near the Persian Gulf are 

likely to expand, including arid but still habit-

able regions of Iran. “Lut would be a good 

lab to study what an extreme environment 

would look like,” AghaKouchak says. 

To probe such questions more deeply, 

Akhani’s team plans to return in the spring. 

Among other things, they will bring more 

sophisticated instruments for measuring soil 

moisture and set up camera traps to study 

the ecology of the desert fox and other crea-

tures in more detail. They also hope to deci-

pher at a molecular level how the life forms 

adapt to broiling heat, Akhani says. In 2018, 

they may even attempt a summer expedition. 

“If we go then, we probably need to bring 

a physician,” says AghaKouchak, who has-

tens to add, “I can’t wait to go back.” 

j

The remains of birds that blundered into the desert (top) apparently help support an ecosystem of animals 

including Rüppell’s foxes (bottom left) and geckos (bottom right), along with numerous insects.

P

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Richard Stone (December 15, 2016) 

Some like it hot

 

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